Transparent thermoplastic compositions of polyvinyl chloride, copolymers of alkenyl aromatic hydrocarbon and acrylonitrile, and a mutualizing agent and method of making the same



3,fi43,7% Patented July 10, 1862 3,043,795 TRANSPARENT THERMOPLASTIC COMPOSITIONS OF POLYVINYL CHLORIDE, COPOLYMERS OF ALKENYL AROMATIC HYDROCARBON AND ACRYLONITRILE, AND A MUTUALIZING AGENT AND METHOD OF MAKING THE SAME Carleton W. Roberts, Midland, and Daniel H. Haigh, Beaverton, Mich, assignors to The Dow Chemical Company, Midiand, Mich, a corporation of Delaware No Drawing. Filed Mar. 27, 1959, Ser. No. 802,314 9 Claims. (Cl. zen-33s This invention concerns new resinous compositions of matter comprising a predominate amount of polyvinyl chloride intimately incorporated with a minor proportion of a thermoplastic copolymer of an alkenyl aromatic hydrocarbon and acrylonitrile, and a mutualizing agent, and relates to a method for making the compositions.

It is known to incorporate a minor proportion of a rubbery copolymer of butadiene and acrylonitrile with polyvinyl chloride to produce compositions which are useful for a variety of purposes. However the relative softness and flexibility of such compositions restricts greatly their utility for many purposes for which theyare otherwise well suited. Attempts to prepare rigid polyvinyl chloride compositions by incorporating normally hard thermoplastic polymers of alkenyl aromatic hydrocarbons with polyvinyl chloride have shown that the alkenyl aromatic hydrocarbon polymers are*in general incompatible with polyvinyl chloride and form translucent to opaque plastic masses which are undesirable.

It has now been discovered that transparent resinous compositions comprising a predominant amount of polyvinyl chloride can readily be prepared by intimately incorporating with the polyvinyl chloride a minor proportion of a normally hard thermoplastic copolymer of an alkenyl aromatic hydrocarbon and acrylonitrile and a mutualizing agent as hereinafter defined.

The term mutualizing agent pertains to certain chemical compounds hereinafter defined which have an action of rendering the polymers compatible with, or soluble in, one another and said agent to produce transparent compositions.

The compositions possess good mechanical properties such as tensile strength, elongation, heat distortion tem'-' perature and rigidity and can readily be molded by usual compression or injection molding operations or by extrusion methods to produce articles suitable for a variety of purposes in the home and industry.

The polyvinyl chloride to be employed in the compositions can be any of the usual commercial grades of polyvinyl chloride having a molecular Weight corresponding to a viscosity characteristic of from 1.1 to 2.5 centipoises as determined for a 2 Weight percent solution of the polyvinyl chloride in ortho-chlorobenzene at 120 C.

The normally hard thermoplastic alkenyl aromatic hy-' drocarbon-acrylonitrile copolymer starting material can be a copolymer containing in chemically combined form from about 25 to 35 percent by Weight of acrylonitrile and from 75 to 65 percent by weight of at least one monoalkenyl aromatic hydrocarbon of the benzene series such as styrene, vinyltoluene, vinylxylene, ar-ethylvinylbenzene, isopropylstyrene or tert.-butyl styrene. Such monoalkenyl aromatic hydrocarbons have the general formula:

Ar-CH CH lecular weight corresponding to a viscositycharacteristic of from about 10 to 60 centipoises as determined for a 10 weight percent solution of the copolymer in methyl ethyl ketone at 25 C.

The polymeric ingredients can be employed in proportions of from about 80 to 95 percent by weight of the polyvinyl chloride and from about 20 to 5 percent by weight of the alkenyl aromatic hydrocarbon-acrylonitrile copolymer, based on the sum of the weights of the polymeric ingredients, but are preferably used in proportions of from 85 to 90 percent by weight of the polyvinyl chloride and from 15 to 10 percent of the alkenyl aromatic hydrocarbon-acrylonitrile copolymer.

The mutualizing agents which render the polymeric ingredients compatible with one another to produce transparent compositions are chemical compounds consisting of the addition reaction products or adducts of hexachlorocyclopentadiene and a vinyl aromatic compound of the benzene series such as styrene, vinyltoluene, vinylxylene, ar-ethylvinylbenzene, isopropylstyrene, tert.-butyl styrene, 2,4-dichlorostyrene, 2,5-dichlorostyrene, ar-chloro styrene or divinylbenzene.

The adducts of hexachlorocyclopentadiene with monovinyl aromatic compounds have the general formula:

wherein Ar represents an aromatic radical of the group consisting of hydrocarbon and chlorohydrocarbon radicals of the benzene series. The adducts of hexachlorocyclopentadiene and divinylbenzene have the formula:

01 01 J; e or i on o i 1 CC]: l (g C012 ll 010 1 CH: H2 001 n n The adducts are preferably adducts of hexachlorocyclopentadiene with a mixture of isomeric metaand para divinylbenzenes or a monovinyl aromatic compound having the general formula:

wherein X and Y each represent a member of the group consisting of hydrogen, chlorine and lower alkyl radicals containing from 1 to 4 carbon atoms. The adducts can be prepared by reacting hexachlorocyclopentadiene with the vinyl aromatic compounds by procedure similar to that decribed in U.S. application Serial No. 717,812, now U.S. Patent No. 2,952,711, filed February 27, 1958, by Carleton W. Roberts.

In brief, the adducts of hexachlorocyclopentadiene and the vinyl aromatic compounds can be prepared by reacting hexachlorocyclopentadiene with the vinyl aromatic compound at temperatures between 70 and 180 C., suitably at temperatures between and C., in an inert organic solvent such as benzene, toluene, Xylene, ethylbenzene, chlorobenzene, ortho-dichlorobenzene, heptane, octane or petroleum ether, at atmospheric pressure or thereabout. The reaction is preferably carried out by, dissolving the hexachlorocyclopentadiene in the organic solvent, e. g. heptane or toluene, heating the mix- .tureto its refluxing temperature and thereafter adding the vinyl aromatic compound, preferably mixed with anproportions corresponding to approximately one gram molecular proportion of the hexachlorocyclopentadiene per gram equivalent vinyl radical, e.g. CH=CH group, in the vinyl aromatic compound, and at about the rate it is consurned'in the reaction. The reaction is usually exothermic and proceeds rapidly. After adding the vinyl aromatic compound, the resulting mixture is usually refluxed or maintained at reaction temperatures between 70 and 180 C. for a period of from one to four hours or more to complete the reaction. The adduct product is recovered in usual wa-ys, e.g. by crystallization or by distillation methods, depending upon whether the product is a crystalline or a liquid material.

A number of the adducts of hexachlorocyclopentadiene and the vinyl aromatic compounds employed as mutualizing agents in making the compositions of this invention are new chemical compounds, and are described and claimed in our copending application Serial No. 802,295,

filed on even date herewith, now US. Patent No. 2,952,712. p

The mutalizing agents, i.e. the adducts of hex-achlorocyclopentadiene and the vinyl aromatic compounds herein specified, can be employed alone or as a mixture of any two or more of such adducts and in amounts corresponding to from about to 20, preferably from to 15, parts by weight of one or more of said adducts per 100 parts by weight of the sum of the weights of the polymeric ingredients.

The compositions are prepared by heat-plastifying and mechanically working the polymeric ingredients in admixture with one another in usual ways such as by compounding on heated rolls, in a Banbury mixer or a plastics extruder at temperatures between about 140 C. and 240 C. until a homogeneous and uniform composition is obtained. In general, compounding of the heat-plastified ingredients with one another at the above-mentioned temperatures for periods of from one to twenty minutes is satisfactory. The ingredients should not be compounded at the elevated temperatures for prolonged periods of time such as to result in deterioration or breakdown of the polymeric ingredients. It may be mentioned that when compounding the polymeric ingredients with one another and the mutualizing agent best results are usually obtained by first compounding or milling the acrylonitrilealkenyl aromatic hydrocarbon copolymer with the mutualizing agent to obtain a uniform composition, and in the case of a crystalline mutualizing agent, at temperatures near or above the melting point of said agent, and thereafter adding the polyvinyl chloride, suitably as a powder or in molten form to the heat-plastified mass and milling or compounding the resulting mixture at heatplastifying temperatures to blend the polymeric ingredients and the mutualizing agent into a uniform composition. The compostiion iscooled and cut or ground to a granular form suitable for molding.

The compositions of the invention consists essentially of the polyvinyl chloride, the alkenyl aromatic hydrocarbon-acrylonitrile preferably styrene-acrylonitrile, copoly- 'mer and the mutualizing agent in the proportions hereinbefo're stated, but as is usual with polyvinyl chloride compositions, the compositions preferably contain a small amount, suitably from 1 to 5 percent by weight based on the Weight of the composition, of a stabilizing agent intimately incorporated therewith. Suitable stabilizing agents are basic lead carbonate, lead ortho-silicate, cadmium stearate, cadmium laurate, cadmium octoate, cadmium ricinoleate, barium cadmium laurate, dibutyl tin mercaptide, cadmium 2-ethylhexoate, sodium ricinoleate and dibutyl tin S,S' bis(3,5,S-trimethylhexylmercaptoacetate).

Other additives such as plasticizers, flow agents, mold 'release agents, dyes, pigments, or lubricants can be incorporated with the compositions, but are not required in the invention. Such additives, when used, are usually employed in amounts of from 0.5 to 20 percent by weight of the composition.

As previously mentioned, the new compositions are transparent resinous compositions possessing good mechanical properties and rigidity. They can be molded to form plastic articles such as sheet, film, rod, bars, tape, strips, boxes, cups, containers, etc., which are useful for a variety of purposes in the home and industry.

The following examples illustrate ways in which the principle of the invention has been applied, but are not to be construed as limiting its scope.

EXAMPLE 1 Preparation of Adduct of H exachlorocyciopentadiene and Divinylbenzene (A) A charge of 2727 grams (10 moles) of hexachlorocyclopentadiene and 5 liters of n-heptane was placed in a glass reaction vessel equipped with a reflux condenser and stirrer. The mixture was stirred and heated to its reflux temperature. benzene fraction containing 75 percent by weight of a mixture of isomeric metaand para-divnylbenzenes in proportions of about 65 percent by weight of the metadivinylbenzene and 35 percent by weight of the paradivinylbenzene was added over a period of 1.5 hours. The resulting mixture was stirred and maintained at a refluxing temperature for a period of 35 hours, then was cooled to a temperature of 5 C., with stirring. A crystalline material separated from the liquid. The crystalline material was separated from the liquid by filtering and was washed with a small amount of n-heptane and was dried. There was obtained 2420 grams of a mixture of isomeric metaand para-bis(1,4,5,6,7,7 hexachlorobicyclo[2.2.1]-5-hepten-2yl)benzenes as a white crystalline product melting at 175 C.

The mixture of isomeric metaand para-bis( 1,4,5,6,7,7- hexachlorobicyclo [2.2. 1] -5-hepten-2yl) benzenes is usually obtained as a white crystalline product melting at a tem perature between about and 180 C. depending upon the relative proportions of the metaand para-isomeric compounds in the mixture. The pure meta-bis(l,4,5,6,7, 7-hexachlorobicyclo [2.2. 1 -5-hepten-2yl) benzene has a melting point of about 2l0-215 C., and the pure parabis(1,4,5,6,7,7-hexachlorobicyclo[2.2.1] 5 hepten-2yl)- benzene melts at about 285 295 C., but a mixture of the isomeric compounds melting at temperatures between 140 and 180 C. is advantageously employed in making the compositions of the invention.

(B) A charge of 50 grams of a resinous copolymer of 70 percent by weight of styrene and 30 percent of acrylonitrile, having a viscosity characteristic of 12 centipoises as determined'for a 10 weight percent solution of the copolymer in methyl ethyl ketone at 25 C. was heat-plastified by milling the same on a pair of laboratory rolls at a temperature of 180 C. A charge of 50 grams of the crystalline adduct melting at C., prepared above, was added and was intimately blended with the heated copolymer. Thereafter, 450 grams of polyvinyl chloride containing 3 percent by weight of dibutyl tin S,S-bis(3,5, S-trimethylhexylmercaptoacetate) as stabilizer, was added; The resulting mixture was compounded on the rolls at a temperature of C. for a period of 10 minutes to former homogeneous composition, then was removed from the rolls, was allowed to cool to room temperature and was crushed to a granular form. Portions of the composition were injection molded to form test pieces of /2 x Ms inch cross section. These test pieces were used to determine the tensile strength and percent elongation for the product employing procedure similar to those described in ASTM D638-49T. Impact strength was determined by procedure similar to that described in ASTM D256-47T. Other molded test pieces were used to deter- Thereafter, 743 grams of a divinyl-f mine a heat distortion temperature for the composition employing a procedure similar to that of Heirholzer and Boyer, see ASTM Bull. No. 134 of May 1945. The com position had the properties:

. 6 ployed in making the same. adduc is employed to identify the reaction product of the 'hexachlorocyclopentadiene and the divinylbenzene for brevity.

TABLE I Starting Materials Product RUJl Polyvinyl Copoly- Tensile Elonga- Notched Heat No. Ohlomer, Bls- Strength, tion, Impact Distor- Color ride Parts by Adduct, 1bs./sq. in. percent Strength, tion Parts by Weight percent Ft.-lbs. Temp., Weight C.

90 10 9, 050 64.8 0.52 76 Clear. 90 10 9, 500 58. 4 0. 53 42 D0. 90 10 9, 520 62.1 0. 56 73 Do. 85 16 5 9, 920 83. 7 0.53 73 Do. 85 15 10 9,700 46.2 0.54 80 Do. 85 15 15 9,690 101.9 0.53 73 D0.

Tensile strength 9,500 lb SJSq. in. EXAMPLE 4 58.4 ercen 5 25523 p strength 0 53 g t In each of a series of experiments, a charge of a copoly- Heat distortion pg zg C mer of 70 percent by weight of styrene and 30 percent of Color Transparent. acrylonitrile' and 1,2,3,4,7,7-hexachloro-6-(4-tert.-buty1- phenyl)-bicyclo[2.2.1]hept-2-ene, i.e. the adduct of 4- In contrast, a composition prepared from 45 parts by weight of a copolymer of 81 percent by weight of styrene and 19 percent of acrylonitrile, 455 parts of stabilized polyvinyl chloride and 57.5 parts of the adduct melting at 175 C. as mutualizing agent, was an opaque product having an elongation of only 23.9 percent.

EXAMPLE 2 A charge of 400 grams of stabilized polyvinyl chloride, 100 grams of a resinous copolymer of 70 percent by weight of styrene and percent of acrylonitrile and 100 grams of the adduct of hexachlorocyclopentadiene and divinylbenzene melting at 175 C. as mutualizing agent, was compounded into a uniform composition by procedure similar to that employed in Example 1. The composition had the properties:

tert.-butylstyrene and hexachlorocyclopentadiene, prepared by procedure similar to that described in Example 1 for making the adduct of hexachlorocyclopentadiene and divinylbenzene, a white crystalline material melting at 103.5-104 C., in proportions as stated in the following table was milled together on compounding rolls at a temperature of 180 C. Thereafter, the mixture was blended with polyvinyl chloride containing 3 percent by weight of dibutyl tin S,S-bis( 3,5 ,S-trimethylhexylmercapto acetate), as stabilizer, in amount as stated in the table by milling the ingredients on the heated rolls at a temperature of 180 C. for a period of 10 minutes to form a homogeneous composition. The product was injection molded to form test pieces. These test pieces were used to determine the properties for the composition employ- Tensile strength 9,930 lbs/sq. in. Elnngatinn 101.9 percent. mg pr0ce.dure.s sumlar to s employe.d.m Exampl? Notched impact strength 056 Table II ldentlfies the compositlons by giving proportions Heat distortion temperature 75 C, of the ingredients used in preparing the same, and gives C l r Transparent. the properties determined for the products.

TABLE II Starting Materials Product Run Polyvinyl Copoly- Notched Heat N o. O hlomer, Ad pl not Tensile Elonga- Impact Distorride, Parts by percent Strength, tion, Strength, tion Color Parts by Weight lbs/sq. in. percent Ft.-lbs. Temp, Weight 0.

1 95 6 l0 9, 700 38. 1 0. 53 72 clear. 2 90 10 10 9, 740 35. 9 0.36 74 Do. 3 85 15 10 9, 830 52. 3 0. 37 74 D0. 4 80 20 10 9, 750 82. 3 0. 40 77 Do.

EXAMPLE 3 EXAMPLE 5 In each of a series of experiments, a charge of a copolymer of 70 percent by weight of styrene and 30 percent of acrylonitrile, and an amount of the adduct of hexachlorocyclopentadiene and divinylbenzene melting at 175 C. as stated in the following table was compounded with a charge of the stabilized polyvinyl chloride, employing a procedure similar to that employed in Example 1, to form a homogeneous composition of the ingredients in proportions as stated in the following table. The compositions were tested employing procedures similar to those employed in Example 1. All of the compositions formed transparent moldings. Table I identifies the compositions by giving the proportions of the ingredients em- In each of a series of experiments, a charge of grams of a copolymer of 70 percent by weight of styrene and 30 percent of acrylonitrile having a viscosity characteristic of 11 centipoises as determined for a 10 weight percent solution of the copolymer in methyl ethyl ketone at 25 C. was milled on compounding rolls at a temperature of C. for a period of 6 minutes, together with an amount of the adduct of 4-tert.-butylstyrene and hexachlorocyclopentadiene melting at 103.5-104 C., as stated in the following table. A charge of 400 grams of polyvinyl chloride containing 3 percent by weight of dibutyl tin S,S'-bis(3,S,S-trimethylhexylmercapto acetate) as stabilizer was added. The resulting mixture was com- In the table the term bispounded on the rolls at a temperature of 180 C. for a period of 10 minutes to form a homogeneous composition. The composition was molded and tested employing procedures similar to those employed in Example 1. Table 8 taining 54.25 percent by weight of chlorine by analysis.

(2) A mixture of isomeric 1,2,3,4,7,7-hexach1oro-6- (metaand para-ethylphenyl)bicyclo[2.2.1 ]hept-2-ene, a colorless liquid boiling at 194 C. at 2.2 millimeters III identifies the compositions and gives the properties 5 absolute pressure having a refractive index N 1.5750 determined for the product.

TABLE! III Starting Materials Product Run Polyvinyl Copoly- Notched Heat N o. Chlomer Adduct, Tensile Elonga- Impact Distorride, Parts by percent Strength, tion, Strength, tion Color Parts by Weight lbs/sq. in. percent Ft.-lbs. Temp.,

Weight 0.

80 20 7,350 121.3 0.34 83 opaque. 80 20 8,000 134.5 0.48 79 clear. so 20 8,820 144.0 0. 35 70 Do. 30 15 9,650 74.8 0.35 73 D0.

EXAMPLE 6 and containing 52.42 percent by weight of chlorine by In each of a series of experiments, a charge of 55 analysls' grams of a resinous copolymer of 70 percent by weight (3) hexachloro (2,4 of styrene and 30 percent of acrylonitrile having a visl i 'i whlte (.n'ystanme material cosity characteristic of 11 centipoises as determined for meltmfg at 127 2 (fontammg 63-13 Percent a 10 weight percent solution of the copolymer in methyl by Welght of chlonne by analyslsethyl ketone at 25 C. was heat-plastified by milling the hexachloro 6 f (4 tert' butylphejn same on a pair of laboratory compounding rolls at a temynbicyclo 3 a whlte qystallme mammal perature of C. The heabsoftelmd copolymel. was melting at 103.5 104 C. and containing 48.87 percent then compounded with 55 grams of an adduct of hexaby Welght of chlonne by analyslschlorocyclopentadiene and a monovinyl aromatic com- (5) f hexachlw 6 phFnyl blcyclo pound as identified in the following table. Thereafter, z a h crystanme matenal at 445 grams of polyvinyl chloride containing 3 percent 76 C. and contaimng 57.9 percent of chlor ne by analysis. by Weight of dibutyl fin ssgbise,s,5 trimethylhexyl S1m1lar results are obta ned by substituting the adduct mercapto acetate) as stabilizer was added. The resulting of hexachlomcyclopentadlene with vmylxylene P mixture was milled on the rolls at a temperature of 180 Pylstyrene, ar-ethylchlPmstyrefle ar'chlomvmyltoluenei for a period of 10 minutes, then was removed from ar-chlorostyrenecr ar-lsopropylchlorostyrene, for the adthe rolls, was allowed to cool to room temperature and ducts P y m the expenmentswas crushed to a granular form. Portions of the com- 40 We dalm' position were molded to form test pieces. The properties A of eomp'nsmg 5 to 20 for the composition were determined employing proce- Perm!t by welgh't a resmous the nn0plaSt1c P (lures Similar to those employed in Example Table mer of from to 75 percent by weight of at least one IV identifies the experiments and names the monovinyl alkenyl ammatlc hydrocal'bon havmg the general aromatic compound which was reacted with the hexa- 1a 2 Wherem TePree11tS an aromatic y" chlorocyclopentadiene to form the adduct employed as drocarbon radical of the benzene senes, and from 35 to 25 mutualizing agent in said experiment. The table also percent of acrylonitrile, intimately incorporated with from gives the properties determined for the composition. 95 to 80 percent by weight of polyvinyl chloride, and

7 TABLE IV Mutuahzing Agent Product Run No. Tensile Elonga- Notched Heat Dis- Color Adduct of Hexachloro- Strength, tion, Impact tortion cyclopentadiene Withlbs./sq. in. Percent Strength, Temp,

ft.-lbS. C.

1 Mixture of metaand 9,975 34.5 0.32 66 clear.

para-vinyltoluenes. 2 Mixture of metaand 9,550 31.2 0.40 64 Do.

para ethylvinylbenzenes. 2, 4-dichlor0styrene 9,475 45.3 0.36 66 Do. 4-tert.-butyl styrene. 10,100 36.1 0.38 68 D0. Styrene 9,640 32.5 0.40 67 Do.

The adducts employed in the experiments were prepared 65 with from 5 to 20 percent, based on the sum of the by reacting hexachlorocyclopentadiene with the mono Weights of the polymeric ingredients, of an adduct of vinyl aromatic compounds employing procedure similar hexachlorocyclopentadiene and a vinyl aromatic comto that described in Example 1, and separating the prodpound selected from the group consisting of divinylbennot from the reacted mixture in usual Ways, e.g. by cryszene, monovinyl aromatic hydrocarbons of the benzene tallization or distillation methods. The adducts were 70 series and nuclear chlorinated monovinyl aromatic bychemical compounds characterized as follows: drocarbons of the benzene series.

(1) A mixture of isomeric 1,2,3,4,7,7-hexachloro-6- 2. A composition of matter comprising from 5 to 0 metaand para-tolylbicyclo[2.2.1]hept-2-ene. a colorless percent by Weight of a resinous thermoplastic copolymer liquid boiling at 163.5 C. at 0.8 millimeter absolute of from 65 to percent by weight of styrene and from pressure having a refractive index N 1.5828 and con- 75 35 to 25 percent of acrylonitrile intimately incorporated with from 95 to 80 percent by weight of polyvinyl chloride, and with from to 20 percent based on the Sum of the weights of the polymeric ingredients, of a mutualizing agent consisting of an adduct of hexachlorocyclopentadiene with a vinyl aromatic compound selected from the group consisting of divinylbenzene, monovinyl aromatic hydrocarbons of the benzene series and nuclear chlorinated monovinyl aromatic hydrocarbons of the henzene series.

3. A composition as claimed in claim 2, wherein. the adduct is an adduct of hexachl-orocyclopentadiene and 4-tert.-butylstyrene.

4. A composition as claimed in claim 2, wherein the adduct is an adduct of hexachlorocyclopentadiene and a mixture of metaand para-divinylbenzenes, which adduct has a melting point between 150 and 180 C.

5. A composition as claimed in claim 2, wherein the adduct is an adduct of hexachlorocyclopentadiene and vinyltoluene.

6. A composition as claimed in claim 2, wherein the adduct is an adduct of heXachlorocyclopentadiene and a mixture of metaand para-ethylvinylbenzenes.

7. A composition as claimed in claim 2, wherein the adduct is an adduct of hexachlorocyclopentadiene and 2,4-dichlorostyrene.

8. A composition as claimed in claim 2, wherein the adduct is an adduct of hexachlorocyclopentadiene and styrene.

9. A method of making a transparent composition of matter which comprises heat-plastifying a resinous thermoplastic copolymer of from to percent by weight of an alkenyl aromatic hydrocarbon having the general formula ArCH=CH wherein Ar represents an art matic hydrocarbon radical of the benzene series, and from 35 to 25 percent of acrylonitrile at temperatures between and 240 C. and intimately incorporating with the heat-softened copolymer an adduct of hexachlorocyclopentadiene and a vinyl aromatic compound selected from the group consisting of divinyl benzene, monovinyl aromatic hydrocarbons of the benzene series and nuclear chlorinated monovinyl aromatic hydrocarbons of the benzene series, then intimately incorporating the resulting mixture with polyvinyl chloride at temperatures between and 240 C. to form a homogeneous composition, said polymeric ingredients being in proportions of from 5 to 20 percent by Weight of the copolymer of the alkenyl aromatic hydrocarbon and acrylonitrile and from 95 to 80 percent of the polyvinyl chloride and said adduct being in amounts of from 5 to 20 percent, based on the sum of the weights of the polymeric ingredients.

References Cited in the file of this patent UNITED STATES PATENTS 2,606,910 Herzfeld et a1 Aug. 12, 1952 2,646,417 Jennings July 21, 1953 2,902,460 Jennings et a1. Sept. 1, 1959 2,952,711 Roberts Sept. 13, 1960 2,952,712 Roberts et a1. Sept. 13, 1960 

1. A COMPOSITION OF MATTER COMPRISING FROM 5 TO 20 PERCENT BY WEIGHT OF A RESINOUS THERNOPLASTIC COPOLYMER OF FROM 65 TO 75 PERCENT BY WEIGHT OF AT LEAST ONE ALKENYL AROMATIC HYDROCARBON HAVING THE GENERAL FORMULA AR-CH=CH2 WHEREIN AR REPRESENTS AN AROMATIC HYDROCARBON RADICAL OF THE BENZENE SERIES, AND FROM 35 TO 25 PERCENT OF ACRYLONITRILE, INTIMATELY INCORPORATED WITH FROM 95 TO 80 PERCENT BY WEIGHT OF POLYVINYL CHLORIDE, AND WITH FROM 5 TO 20 PERCENT, BASED ON THE SUM OF THE WEIGHTS OF THE POLYMERIC INGREDIENTS, OF AN ADDUCT OF HEXACHLOROCYCLOPENTADIENE AND A VINYL AROMATIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF DIVINYLBENZENE, MONOVINYL AROMATIC HYDROCARBONS OF THE BENZENE SERIES AND NUCLEAR CHLORINATED MONOVINYL AROMATIC HYDROCARBONS OF THE BENZENE SERIES. 